The debate about the beginnings of life has always and will always have a theological or at least spiritual component. But the debate over its physical origins has a great deal more to do with evidence. And evidence seems to be mounting that we’re not from around here. Did life — or the ingredients for life — get to this planet by hitching a ride on an asteroid or comet? New research indicates that it’s extremely plausible.
“Panspermia” is the technical name for the theory that life exists throughout the universe and is distributed to other worlds — almost certainly as primitive microbes — via asteroids, comets, and planetoids. A related theory, “Pseudo-Panspermia,” suggests that life itself isn’t what’s shuffled back and forth throughout the universe. Instead, these rocks probably carry organic molecules, the building blocks for life, and seed on other planets and moons with the ingredients for life itself. That idea is probably the most scientifically feasible.
A team of scientists at the Institut de Chime de Nice (CNRS) in Paris have just published a study that goes a long way to the pseudo-panspermia perspective. In the newest issue of Science, the researchers suggest that ribose — a key sugar found in the genetic material of all organisms — might be formed on ices within comets. Ribose is a key part of nucleic acids like DNA and RNA. The formation of such a compound on a comet would indicate that the fundamental ingredients for life aren’t simply capable of traveling across interstellar space to different worlds, but can also form in space. We’ve already found amino acids on comets, cosmic dust laced with complex organic matter, and basic sugars in other star systems. The Ribose finding would amount to more evidence stacking up.
To be clear, the researchers haven’t actually found ribose on a comet. Instead, they’ve used data gathered by other scientists to artificially simulate the evolution of interstellar comet ice under astrophysical conditions in a lab, and were able to derive ribose as a result.
The artificial comet, produced at the Institut d’Astrophysique Spatiale, was made by mixing water, methanol, and ammonia in a high vacuum chamber at minus 200 degrees Celsius. The researchers added dust grains with ice that act as the raw material of comets, and irradiated the whole thing with ultraviolet light. When the sample was heated to room temperature — as a comet would be as it approaches the sun — it was found to have developed simple sugars.
We still have to wait to confirm whether ribose can actually be formed on a real comet, but the implications of this new discovery are nevertheless huge. The more we learn about what kinds of compounds are laying low within asteroids and comets, the more support panspermia-type theories obtain. Perhaps life really did come to Earth on a comet. And perhaps we could send life to other worlds by sticking some organic compounds on our own artificial comet and firing it off into the depths of the universe.